Phonograph



July 5, 1932. R. Y. BARROWS ET AL 1,865,550

PHONOGRAPH Filed Nov 5, 1928 3 Sheets-Sheet 3 H 0 Fold PGurHs,RoberYBarrow 5,decd.,

Patented July 5, 1932 UNITED STATES PATENT OFFICE ROBERT Y. BARROWS,DECEASED, .OF RUTHERFORD, NEW JERSEY, BY GRACE A. BARROWS,ADMINISTRATRIX,'OF EAST ORANGE, NEW JERSEY, AND HAROLD P.

CURTIS, OF JARDINE, MONTANA rnonoenarn Original applioa tionlflledJanuary 27, 1921, Serial No.440,384. Divided and this application filedNovember i 5, 1928. Serial No. 317,397.

This application is a division of the application of Robert Y.Barrowsand" Harold P. Curtis for phonograph, filed January 27, 1921,Serial No. 440,384, and allowed April LGth, 1928..

This invention relates to improvements in talking machines and has forits principal object theprovision of a talking machinedesigned for andcapable of reproducing a musical performance, s eech' or the like,exactly and truthfully in tone quality or timbre and without the thinand nasal whine characteristic of most phonographic reproductions andheretofore capable only of 15. amelioration. L I

A very important object of the invention is to provide a novel; andgreatly improved amplifying horn or sound chamber wherein p the aircolumn will be caused to vibrate and reproduce music or speechfaithfully, artistically and pleasin 1y. I

Still another 0%ject of the invention is to provide a talking machine inwhich the amplifying-horn or chamber is built into and forms a permanentpart of the cabinet which encloses all the mechanism;

Other and further objects, such as cheap ness and simplicity inmanufacture, efficiency in action, durability in service, and a generalimprovement of the art will appear hereinafter in the description,pointed out in the appended claims, and illustrated in the drawingswhich will be referred to later.

'- In order to make a complete disclosure of our inventionit will benecessary to correct some prevalent misconceptions as to the action ofthe air in the resonator or horn of a honograph. I

ound is an idea or impression caused by with the diaphragm of thereproducer at the other. It is this confined body of air in thephonograph horn that is exactly analogous to the sounding board of apiano. As the vibrating string of a piano, being in direct.

a complicated succession of air vibrations contact through the bridgewith the sounding board thus transmits its feeble impulses to alargearea of free air, so the small vibrating diaphragm of the reproducertransmits its impulses to a comparatively great area of the free air,through theiresonant bodyof air confined within the horn. As the pianosounding board must be held in shape by a massive and rigid frame,somusttheair column in the horn be positively confined in such a way asto prevent the sound waves disintegrating while they are beingcommunicated to larger and larger areas ofthe' air column. For thispurpose the horn must be constructed air tight and of non-vibratingmaterial. An analysis of the spiral line on a'revolving phonographrecord will establish the fact that consequent systems of agitation inthe free air are complicated to an extreme degree; Thus in the usualtwelve inch record this line may be about seven hundred feet long andtravels under the stylus at the rate of about thirty inches per second.If the note tenor C be played by one trombone, its record line will showjogs spaced about one quarter of'an inch apart, which, in reproducing,will give vibrations of about one hundred and thirty to the second andrepresent the fundamental pitch of the tone. If this were all, the notewould have no character either as a trombone or anythin else. It is thecomplex accompaniment of armonic over-tones that determines the qualityof the tone. In the case of the trombone the first overtone is theactive, represented by lesser jogs spaced about one eighth'of an inchapart. The next will be the twelfth from the fundamental and so on upthe scale until we rea'chthe limit of intelligible sound where therewill be vibrations atthe rate of about eight thousand to the secondrecorded in our spiral line by jogs about one two hundred and sixtiethof an inch apart. As this is the nature of the record of onlyone noteplayed on a single instrument, the complexity of a record made by anorchestra or chorus can hardly be imagined. Although the sound waves setin motion by the diaphragm are complex, they'are definite in theircharacters and obviously cannot be changed but'only developed .overwidening areas so as to amplify their inherent characteristics.

The horn, tone arm and diaphragm box form the complete acoustic assemblyof a phonograph and faulty design inany one will be fatal to goodresults. The diaphragm is set in motion by the stylus bar which travelsover the record, or beneath which the record travels, the movement beingrelative. Cer ta-in requirements must be complied with in theconstruction of the sound box and other associated parts but the presentinvention is not concerned with these details. It is, however, animportant point that the air column in the amplifying horn must be heldfirmly at all points, from the diaphragm of the sound box to the largeend of the horn, a special joint between the tone arm and amplityinghorn being consequently necessary to prevent leakage. t g

The structural features will be clearly visible from an inspection ofthe drawingswherein:

Figure 1 is a vertical section takenthrough a complete phonographassembly embodying the amplifying horn construction constituting theinvention,

Figure 2 is a vertical: sectional view taken at right angles to Figure1, p t

Figure 3 is a cross sectional view taken on the line 3-3 of- Figure 2,

Figure 4 is a cross section on the line 4-4. of Figure 1.

Referring more particularly to the drawings, the numeral 10 designates,-generally, the cabinet which may be of any preferred size and shape andany suitable material and finish. It is generally customary that such acabinet be provided with a hinged cover 11 which encloses the sound box,tone arm and turntable, designated at 29,40 and 65 respectively. Theturntable is mounted upon a motor board 63- andis ordinarily driven by aspring or other motor indicated at 64. The tone arm 40 oscillates withrespect to a relatively stationary pedestal 43 fixedwithin the cabinet.Suitably secured to the pedestal 43 is a depending cylindrical tube 46extending through the motor board and secured to the upper end of atransition section 51 forming part of a sound amplifying horn which inits entirety is constructed to have a uniformly enlarged cross sectionalarea from one end tothe other. Approximately, the rate of enlargement ismade so as tomake the length of the horn in inches equal substantiallyto one-half of the cross sectional area of the horn in square inches atits outer end. The tone arm 40 carries a depending tubularextension 47rotatably received within the cylindrical tube $6 and having bearingcontact therewith and moving, with the tonearm 40 as the stylus of thesound box passes over the grooves in a record.

As-s'hown, clearly in theidrawings, the trancross sectional area of saidbranches at the bottom being-substantially equal to thecross sectionalarea of the section 52 at its lower end. The branches 545et open attheir upper ends into a common vestibule 55 which is gradually enlargedoutwardly into a doorway 56 provided with a door 57 which swings on ahorizontalv axis:58 and which,.in its: open position, is: adapted to besupported by ashoulder 59 of the cabinet. In order to prevent as far aspossible any dissipation of the energy of the sound waves, it ispreferable to make the walls of the horn of non-vibrating material;Plaster or pressed felt board or the like is satisfactory. A partition60 encloses a storage space 61 for. the reception ofrecords, saidv spacebeing normally closed by a door or doors 62.

In the operation it isof. course apparent that as the stylus is vibratedby the undula' tions in the sound groove of the record, the diaphragm ofthe sound box is. correspondingl-y vibrated, thus setting in motion thecolumn of air within the entire amplifying born or chamber. As: thishorn is intended to be constructed or non-vibrating material it willitself have no period of vibration and cannot set up any interferingwaves; Owing to the peculiar formation of the amplifying horn from. thesection 52, passages 54 and vestibule 55, all of. which progressivelyincrease in their cross. sectional areav throughout, there is providedan extremely long vibrating air column which, it has been discovered, ishighly effective and faithful in. reproducing speech or music. Onaccount of the location of the passages or sections 54: at the oppositesides of the section 52, and the substantially horizontalarrangement ordisposition-bf the vestibule 55, it? is apparent that this extremelylong air column is obtained without any necessity for increasing theusual dimensions of the cabinet, the relative positions of the sectionsbeing such as to obtain the maximum benefit from the space within thecabinet. While it is conceivable that the ratio or proportion might bechanged to some extent, it has been discovered that the mostadvantageousrelation is that the horn or amplifying chamber should havealength in inches substantially equal to onehalf of the number of squareinches in the cross sectional area of' the larger end of the horn. I

\Vhile we have shown anddescribed a certain ratio, as above referred toand a general relationof the amplifying horn or chamber sections to oneanother, and have also indicated, generally, a conventional type of tonearm, turntable and other details, it should be understood that thisdisclosure is merely illustrative of the principles involved as theright is reserved to make all such changes as will not depart from thespirit of the invention or the scope of the claims hereunto appended.

Having thus described the invention, we claim:

'1. In a phonograph, a horn having a length in inches substantiallyequal to onehalf of the cross sectional area of its larger end in squareinches.

2. In a phonograph, a horn having a length in inches substantially equalto one-half of the cross sectional area of its larger end in squareinches, said horn having an internal cross sectional area whichincreases uniform ly from one end to the other.

3. In a phonograph, a horn having a uniform rate of expansion from oneend to the other and a len h in inches substantially equal to one-halthe cross sectional area in square inches at its larger end, said horncomprising sections which are united by an interposed chamber to rectifyand transmit sound waves between said sections.

4. In a phonograph, a horn having a uniform rate of expansion from oneend to the other and a length in inches substantially equal to one-halfthe cross sectional area in square inches at its larger end, said horncomprising sections which are united by an interposed chamber to rectifyand transmit sound waves between said sections, each of said sectionsand said rectifying chamber being symmetrical with respect to a commonplane.

5. In a phonograph, a horn structure comprising a sound vestibule, ahorn section extending downwardly through said sound vestibule, saidhorn section having a cross sectional area which is substantiallyuniformly enlarged from end to end, :a multiple branch horn'sectionextending from the bottom of the first mentioned horn section andopening into said sound vestibule, and having a combined substantiallyuniformly enlarged cross sectional area from end to end, and a soundwave rectifying chamber interposed between said horn sections.

6. In a phonograph, a horn section extending downwardly from said tonearm, a sound wave rectifying chamber, into which said horn sectionopens, another horn section comprising upwardly extending branchesleading from said sound wave rectifying chamber, the first mentionedhorn section having a uniformly enlarged cross sectional area from topto bottom and said branches of the second mentioned horn section havinga com bined cross sectional area at the bottom equal to that of thebottom end of the first men- '"tioned horn section, the combined crosssectional area of said branches being uniformly enlarged upwardl Intestimony wli tures.

ereo'f we aflix our signa-

